/*
 * Copyright 2020 WeBank
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package common

import (
"net"
"net/http"
)

const (
	XForwardedFor = "X-Forwarded-For"
	XRealIP       = "X-Real-IP"
	XClientIP     = "x-client-ip"
)

func RemoteIp(req *http.Request) string {
	remoteAddr := req.RemoteAddr
	if ip := req.Header.Get(XClientIP); ip != "" {
		remoteAddr = ip
	} else if ip := req.Header.Get(XRealIP); ip != "" {
		remoteAddr = ip
	} else if ip = req.Header.Get(XForwardedFor); ip != "" {
		remoteAddr = ip
	} else {
		remoteAddr, _, _ = net.SplitHostPort(remoteAddr)
	}

	if remoteAddr == "::1" {
		remoteAddr = "127.0.0.1"
	}

	return remoteAddr
}
